ATLAS B Physics Performance Update

An update of the B physics performance of the ATLAS experiment is presented. After a short review of B production and decays at LHC, the main features of the ATLAS detector are described, and the present construction status is shown. Physics topics which are presented are: precision measurements, rare decays, and B production. It is shown that despite of recent changes in the trigger strategy and initial detector layout, ATLAS retains an excellent potential for measurements of sin2β and rare dimuon decays. A large spectrum of B physics studies is also feasible -- here we present examples of precision measurements with Bs0 mesons, Bc mesons, and B production